Method of treating low-grade fatty materials



Patented Sept. 12, 1950 METHOD OF TREATING LOW-GRADE FATTY MATERIALS William J. Paterson, Newton Highlands, Mass.,

assignor to Lever Brothers Company, Cambridge, Mass., a corporation of Maine No Drawing. Application July 16, 1946, Serial No. 683,993

Claims. (Cl. 260410.9)

This invention relates to the preparation of high grade, light-colored fatty materials from low grade fatty stock. More particularly, it relates to the preparation and recovery of lightcolored lower alkyl esters of fatty acids from dark-colored fatty oils, fats and greases, especial- 1y those containing an appreciable amount of free fatty acids. It relates especially to a method of preparing the lower alkyl esters from the fatty acids in low grade stocks by treatment of the stocks with a lower alkanol vapor in the presence of an insoluble inorganic oxygenated compound as a catalyst, at temperatures far above the boiling point of the alkanol.

There is a great demand for white or lightcolored soaps, and the available supply of high grade fatty stock such as tallow and oils, is insufficient to meet this demand.

The large amounts of commercially available low grade fatty stocks, such as renderers tallow and grease, would go a long way toward satisfying the above demand if these low grade stocks could be purified or otherwise converted into light-colored stocks in a commercially feasible manner. The purification methods proposed heretofore leave much to be desired, and the art is still confronted with the problem of converting the very low grade fatty stocks into high grade soaps and the like products in an economical manner.

The objects achieved in accordance with the invention include the provision of methods for recovering high grade, light-colored fatty materials of good stability from low grade fatty stocks; the provision of methods for the manufacture of white or light-colored soap products from dark-colored low grade fatty stocks; the provision of methods for preparing and recovering high grade, light colored lower alkyl esters of fatty acids from dark-colored low grade fatty stock; the provision of methods for the recovery of the fatty acid components of low grade stock in high yields; the provision of methods of recovering the glycerol component of low grade fatty stocks in an economical manner and in concentrated form; the provision of methods for the economical recovery of valuable by-products from low grade fatty stocks; and other objects which will become apparent as embodiments of the invention are set forth hereinafter.

In accordance with the invention, it has been discovered that low grade, dark-colored fatty stock containing an appreciable amount of free fatty acid (e. g. over 3 weight percent) may be converted to lower alkyl esters of fatty acids by treatment with vapor of a lower alkanol in the presence of an insoluble material as a catalyst and at temperatures above about 150 C., and preferably at least twice the boiling temperature of the alkanol, but below temperatures at which the alkanol is dehydrated. Reaction conditions are adjusted so that substantially all of the free fatty acid in the stock is converted to its lower alkyl ester. Upon distillation of the reaction mass or mixture, water-white or light colored alkyl ester of good stability may be obtained.

In one aspect of the invention, the above reaction mass or mixture containing the unseparated alkyl ester, unreacted glycerides and any intermediate reaction products, is separated from the insoluble catalyst, cooled to a temperature in the range of about 30 to C. and treated with liquid lower alkanol in the presence of a soluble alkaline catalyst. The liquid alkanol reacts with the glyceride and forms the lower alkyl esters of the fatty acid components of the glyceride, and glycerol as a by-product. After the reaction, the alkaline catalyst is neutralized and the reaction mass allowed to stand. After a short period of standing, the material readily separates into two layers, the upper layer contains substantially all of the crude alkyl esters of the fatty acid from both the free fatty acid and the glyceride in the fatty stock, most of the unreacted fatty material, alcohol, glycerol and soap; and the lower layer contains most of the glycerol, a negligible amount of unreacted fatty material, alcohol, a negligible amount of the ester, and soap. For practical purposes, the upper layer contains the ester and the lower layer contains the glycerol.

The upper or crude ester layer is separated, washed with a small amount of water to remove methanol, glycerol and soap, and then subjected to distillation at reduced pressures. A high grade light-colored, color-stable lower alkyl ester product is obtained as distillate, in very high yields. The still residue contains most of the unsaponifiables and other impurities of the fatty stock.

In another aspect of the invention, the treatment of the fatty stock with the lower alkanol vapor in the presence of insoluble inorganic oxygenated material as catalyst at temperatures above about C. and under such reaction conditions, such as amounts of reactants and contact time, esterifies substantially all the free fatty acid in the stock, and also alcoholizes a substantial portion of the glyceride. The resulting reaction mass or mixture, after separation from the insoluble catalyst, contains alkyl esters and also mono-, di-, or tri-glycerides. The reaction mass is subjected to distillation and the alkyl esters, glycerol, mono-glycerides and di-glycerides are each recovered in relatively pure form. The relative proportions of these materials in the mixture will depend upon the free fatty acid content of the original fatty stock and the degree of alcoholysis of the original glycerides.

Alternatively, the above reaction mass or mixture of esters and partial glycerides may be cooled and treated with liquid lower alkanol in the presence of a soluble alkaline catalyst and further processed, as set forth hereinbefore, in order to recover all the fatty components of the stock as the high grade alkyl esters.

In still another aspect of the invention, either of the above reaction masses or mixtures, resulting from a liquid-vapor reaction step, after separation from the insoluble catalyst, may be further treated in a liquid-vapor mannerwith alkanol vapor at a temperature above about 150 C. and below the alkanol dehydration temperature in the presence of an insoluble material as catalyst for the alcoholysis of the glyceride. The reaction mass or mixture resulting therefrom is separated from the insoluble catalyst and further processed, as above, to recover the lower alkyl esters in relatively pure form.

In yet another aspect of the invention, the liquid fatty stock is treated with the lower alkanol vapor in the presence of insoluble inorganic oxygenated material as catalyst at temperatures above about 150 C. Th free fatty acid component is esterified and substantial amounts of the glycerides are alcoholized. The reaction mass or mixture comprises largely alkyl esters. It may be separated from the insoluble catalyst and further processed as above to recover the lower alkyl esters in relatively-pure form.

Where the fatty stock is substantially all converted to alkyl esters and glycerol by any of the above processes the ester may be separated from the glycerol by settling, centrifugal, solvent extraction, or other known separation processes. The separated lower or glycerol layer may be alkaline, e. g. due to soluble alkaline catalyst; if so, it is acidified. This causes a dark, fatty part (upper layer) to separate and this part contains most of the colored impurities of the starting material'and carried with the glycerol. This dark, fatty layer may be separated from the glycerol and then added to a new charge of fatty stock. If desired, after acidification, the crude glycerol fraction may be heated to refluxing to convert the fatty acids from the soap to lower alkyl esters. If necessary, additional alcohol may be added. The resulting crude ester forms a separate layer upon standing and may be separated from the glycerol and recovered as above.

The glycerol may be recovered in concentrated form. At most, it contains only small amounts of alkali salts and free mineral acid as impurities. The latter may be neutralized. The glycerol may be purified by distillation at reduced pressures. However, the glycerol may be utilized without purification for some purposes, for example in the manufacture of alkyd typ resins.

The wash liquors from crude ester (upper layer) may be worked up to recover the glycerol therein in the usual manner, and the latter may be purified and concentrated by distillation at reduced pressures. The wash liquors and crude glycerol (lower layer) may b combined and then worked up to recover glycerol as above in one operation.

In the first step of the process in which the fatty stock is contacted with alkanol vapor, it is advantageous to employ the insoluble catalyst in granular or pellet form, e. g. in a so-called fixed-bed type catalyst chamber such as a vertical tower containing the pelletized catalyst as a packing. The liquefied fatty stock is introduced at the top of the tower and alkanol vapors at the bottom of the tower. The alkanol vapors pass upward through the tower in countercurrent contact with the liquid fatty stock. If desired, the tower may be divided into zones by plates or the like partitions and diiferent insoluble catalysts used in diiferent zones. For a stock containing large amounts of free fatty acid, a material which is highly efficient as an esterification catalyst may be employed in the zone or zones first contacted by the incoming fatty. stock. For a stock containing relatively little free fatty acid and large amounts of glyceride, e. g. fresh stock or stock containing glyceride and alkyl ester, an insoluble material which is more eflicient as an alcoholysis catalyst may be employed. In general, such a catalyst would be employed in the lower zones.

The insoluble oxygenated material used as a catalyst may be used in powder form, e. g. suspension in the liquid fatty stock which is contacted with the alkanol vapor, and it may be separated from the resulting reaction mass or mixture by filtration, or the like methods.

The reaction zone or zones are maintained at a temperature in the range of above'about C., e. g. by indirect heating. Lower temperatures, such as somewhat above the boiling point of the alcohol, give too little esterification to be of any practical value.

The crud fatty stock may be preheated before contacting the catalyst in the presence of the alkanol vapor. In this preheating step, any water present in the stock will be driven off as water vapor and it is preferred to separately remove this water vapor so that the stock entering the catalyst tower is substantially dry. The water formed during the esterificaton reaction may be removed from the column along with any excess alkanol vapor. It is preferred to pass these exit vapors to a fractionating column to condense out the water and recycle any excess alkanol vapor to the catalyst tower;

It is preferred to preheat the alkanol vapor prior to contact with the catalyst at the tower. However, if desired, liquid alcohol may be introduced and vaporized in the tower.

Recycled alkanol vapors may be used, e. g. those obtained in the distillation of the crude ester product may be charged directly into the catalyst tower in the form of vapor. When recovered or distilled alkyl esters are treated with caustic to convert them into soap and alkanol, this alkanol may be introduced directly into the catalyst tower in the form of vapor, after rectification if aqueous caustic was used for saponification. In such an over-all process, there would be no consumption of the alkanol, and only sufficient alkanol would have to be added to make up for losses.

Any of the steps of the process or any combinations thereof may be conducted in a continuous, a discontinuous or intermittent, or in a batch manner. A continuous process is preferred for commercial scale operations.

The fatty stock treated in accordance with the invention may be any commercially available fatty material. However, the advantages of the invention are more pronounced in the case of low-grade stocks having high free fatty acid content, e. g. 20, or more weight per cent. Even low grade fatty acid stock, such as the acids obtained by acidifying foots or the like, may be used.

The lower alkanols employed in accordance with the invention are the lower monohydric alcohols, such as methanol, ethanol or propanol, and of these methanol is preferred.

The oxygenated material used as a catalyst is one which is solid and insoluble in the reaction mass or mixture and non-volatile under the reaction conditions. In general, these are inorganic, e. g., oxides or oxygen-containing salts of metals. The insoluble oxides of the elements of groups III to VIII of the periodic table are preferred for the esteriiication reaction, and the insoluble oxides of the group II elements may be used for the alcoholysis of glycerides. llfixtures of oxygenated compounds may be used. In general, the catalyst may be prepared by precipitating the corresponding hydroxides and drying at a temperature in the range of 200 to about 500 C. and grinding to the desired particle size. The catalyst may be activated in the catalyst tower under the same temperature conditions as used for the esterfication or alcoholysis reaction and thus there is no requirement of Separate equipment for activating the catalyst.

The catalyst may be naturally occurring and may be a mixture of materials, such as bauxite, various clays, etc., or may be prepared as a mix-- ture or as a relatively pure compound. These materials are sometimes known as contact catalysts and as catalytic solids. The catalysts may be illustrated by alumina, silica, thoria, zirconia, magnesia, calcium oxide, clays, certain salts or the like. Some materials in this class, while operative would be less eificient and would not be selected for a commercial embodiment. Even oxygenated materials which are somewhat soluble in the reaction mixture may be employed if they are supported on or in another material which prevents them from going into solution, e. g. supported on silica gel or alumina gel. A particularly desirable catalyst for both esterification and alcoholysis is formed by co-precipitating alumina and silica in equal mol ratios, e. g. by treating aqueous aluminum nitrate with aqueous sodium silicate, recovering the precipitated gel and Washing, drying and activating it by heating to 500 C. in a current of air before use.

In the second phase of the process, when it is conducted in two steps, in which the material is subject to alcoholysis in the presence of a soluble alkaline catalyst, any convenient all 1aline material may be used as the soluble alkaline catalyst provided it does not introduce substantial amounts of water into the reaction mass. An alkali metal alcoholate or a caustic alkali may be used and approximately 0.1 to about 1.0%, calculated as the hydroxide of the alkali metal is preferred, based on the weight of the fatty stock treated in this step.

The reaction mixture resulting from the treat ment of the low grade fatty stock with the alkanol vapor is particularly suited for direct treatment with a soluble alkaline catalyst and liquid. alkanol for alcoholysis of the glyceride, since the reaction mixture is anhydrous and also substantially free of free fatty acid and thus will give high yields. It is known that even small amounts of water or of free fatty acid, normally present in such stock, interfere with alcoholysis 6 of glyc'erides in the presence of a soluble alkaline catalyst and low yields are obtained therefrom.

In addition, if the reaction mixture contains substantial amounts of monoor di-glycerides, it is particularly suitable for treatment with a soluble alkaline catalyst and an amount of alkanol only slightly more than that required for esterifying the fatty acid components of the glycerides can be used, since such glycerides have much higher solubility in the alkanol and give less viscous and more reactive mixtures.

The following specific illustrations of embodimerits of the invention will serve to point out some of the advantages thereof, but are not to be construed in any sense as limitations of the invention as it is otherwise disclosed and claimed herein.

cc. of a commercial grade of bauxite, of 10 to 20 mesh and about 0.9 bulk density, is placed in the middle three-fifths section of a vertical (1%, I. D.) tube provided with electrical heating means. The top one-"fifth section of the tower is filled with aluminum metal turnings, and serves as a preheating and dewatering zone for the fatty glyceride stock. The lower fifth section of the column is unfilled; it may be used as a preheater for the alkanol vapor if desired.

A typical house grease, dark in color (39 F. A. C.) and containing 18.9% free fatty acid (as oleic), was treated with methanol vapor in the presence of 100 cc. of bauxite catalyst, in the above column, at a fat input rate of 56 grams per hour and a methanol input rate of 30 grams per hour, at various temperatures. The esterification efficiency at each temperature is given in the following table:

Weight Per Tempera- Cent, Original ture, O. F. F. A.

Esterified In another example, dark colored typical house grease (39 F. A. C.) (color standards of the Fat Analysis Committee of the American Oil Chemists Society) containing 18.9% free fatty acids, (as oleic) is liquefied by heating to about 50 C. and charged into the heated column by means of a proportioning pump. Industrial anhydrous methanol is charged by means of a proportioning pump into a vaporizer and the methanol vapors then charged into the lower section of the above column. The hot liquid fat flows downward by gravity against a counter-current stream of the methanol vapors in the presence of the bauxite catalyst. The treated fatty stock is collected in a receiver at the bottom of the column, and the excess methanol vapor containing water, and small amounts of esters of fatty acids, glycerine and fats, passes from the top of the column to a condenser and receiver, or a fractionating column where the alcohol is rectified for re-use. The extent of esterification of the free fatty acid in the glyceride stock charge is determined in the usual way by titration in an alcoholic solution.

In general, a product with about 2% or less free fatty acid is obtained per 100 cc. of catalyst by a throughput of about 56 grams of fat per hour 7 (as anhydrous), and 20 grams of methanol per hour (about of fat throughput), at a temperature in the range of 240 to 260 C., and particularly 250 C.

More generally, for 100 parts of catalyst, fat throughput up to 100 parts per hour, methanol throughput up to 100 parts per hour and temperatures in the range of 200 to 300 C. .may be used. The upper temperature should not be so high as to cause dehydration of the alcohol to form the corresponding ether or olefin. The catalyst column should be of sufiicient size to hold an adequate amount of catalyst, and the catalyst is preferably of 4 to Smesh (Tyler) particle size. The rates of throughput should be such as not to flood the column. Elevated pressures, e. g, up to 150 lbs. per sq. in. gauge may be used. The speed of the reaction is greater at the elevated pressure. The following table shows an optimum relationship of fat and methanol throughput for various particle sizes of catalyst at various pressures:

Fat Throughput Lbs/Hr. per Sq. Ft. Tower Area 250 C.Various Particle Sizes Pressure (lbs/sq. in.

gauge) 15 60 150 Fat/Methanol Wt. Ratio 2/1 3/1 2/1 2/1 Particle Size Tyler Av."Diam. Mesh (inches) The resulting reaction mass analyzes about 2% free fatty acid. It also analyzes about 28.8% lower alkyl ester (e. g., by distillation at 2 to 3 mm. Hg absolute pressure, the distillate boiling in the range of 125 to 180 C.)

There is an alcoholysis equivalent to about 9.0% of the total fatty cid in the original fat, simultaneously with the esterification of free fatty acids .in the presenceofthe insolublecatalyst. If

desired, the glyceride may be recycled through the column in order to :further .alcoholize it, or this may :be accomplished by using a longer catalystbed. For instance, using500 cc. of 8-12 mesh bauxitecatalyst (about 13 deep) and a reaction temperature of 250 C., crude yellow house grease of 18.3 weight per cent free fatty acid was reacted with methanol at hourly throughputs of 190 grams fat (except Run No. .3 which was 103 grams) .per 90 grams alcohol, withrecycling, gave Weight Methyl Esters Pass No. (yieldbased on original charge) 1 20.8 2 (recycle) 26.0 3 (recycle) 36.6

Also, if desired, alkyl esters can .be obtained from the'reaction mass, e. g., by distillation.

The'total reaction mass is mixed with additional anhydrous methanol (about 15% being added, basedonithe weight of the original fat, as anhydrous, which is about 1.8 molsialkanol per mol of combined fatty acid in the glycerides) and 0.4% sodium, agitated for about thirty minutes at about 40 C. and then allowed to stand for about an hour, or even about 15 hours. The glyceride is alcoholized to alkyl esters and glycerine. The reaction mass is then neutralized and made acid, e. g., by adding a, 100% excess of 2% sulfuric acid, and agitated for five minutes at C., and allowed to stand, whereby two layers are formed. The crude ester (upper layer) is separated, washed free from mineral acid with water, and dried. Its ester content, as determined by distilling up to 200 C. at 3 mm. Hg absolute pressure, shows an ester yield of 93.5%.

The water wash from the top layer contains 0.95% of the total fatty acids of the original charge, 8.3% of the glycerol, 15.8% of the sodium, and 53.8% of the excess methanol used in the alkaline catalysis step. Upon neutralization with acid, the fatty acids are liberated from their soaps, and these acids are withdrawn. Upon evaporation of the methanol, preferably with rectification, the aqueous residue contains 6.5% glycerol and 1.8% of sodium sulfate.

The washed ester layer is heated to 150 C. to dry it and the volatile matter condensed and analyzed. The condensate contains 14.5% methanol, equivalent to about 2.2% of the excess methanol used for the alkaline catalyzed alcoholysis.

The crude glycerol (bottom layer) contains about 1.6% of the total fatty acids, 89.9% of the glycerol, 84.2% of the sodium used, and 44.0% of the excess methanol used in the alkaline catalyzed step. Upon neutralization, e. g. with concentrated sulfuric acid, the sodium soap is converted to fatty acid esters, and the esters are drawn oif (it is preferred to add this material to the main bulk of esters in the top layer in commercial operation). After evaporation of the methanol therefrom, the lower layer material consists essentially of anhydrous glycerol containing about 88.8% glycerol and 11.2% sodium sulfate.

The still residue from distillation of the methyl esters amounts to about 1.5% of the weight of the original glyceride charge (as anhydrous). The residue contains about 80.1% fatty acids. In commercial practice these residues can be accumulated and reworked, or added to the incoming charge, in order to recover the fatty acid therefrom as methyl esters.

It is evident from the foregoing that for good yields in the conversion of the free fatty acids into esters, the reaction zone temperature should be far in excess of the boiling point of the lower alkanol. However, the temperature should not be so high as to cause dehydration of the alkanol or of glycerol and 260 C. is regarded as the optimum limiting higher temperature for methanol at atmospheric pressure.

In accordance with the invention, the fatty acid content of the fatty glyceride stock may be substantially completely converted to waterwhite lower alkyl esters. 90% of the glycerol may be recovered in anhydrous form containing a salt such as sodium sulfate.

The still residue from distillation of the alkyl esters may be saponified to recover any fatty material therein. The unsaponifiable material therein is high in sterols. These sterols may be purified if desired, e. g. by solvent extraction. They are valuable, e. g. a8 a lanolin substitute and as source of cholesterol.

It is surprising indeed, that coupled with the marked advantages of the new process as to raw materials, the equipment required is containing free fatty acids with vapor of a lower alkanol at a temperature above about 150 C. and below decomposition temperatures of the alkanol in the presence of an insoluble inorganic oxygenated material as catalyst, the by-product water formed in the esterification reaction being I removed as formed, and said temperature being above the boiling temperature of the lower alkanol at the pressure employed.

2. Method of treating low grade fatty stock containing at least 5% by weight of free fatty L acids which comprises treating said stock with vapor of a lower alkanol at a temperature above about 200 and below decomposition temperatures of the alkanol in the presence of an insoluble inorganic catalyst comprising an inorganic oxide, to form alkyl esters, and separat ing alkyl ester from the reaction mass, the byproduct water formed in. the esterification re action being removed as formed, and said tem= perature being above the boiling temperature of the lower alkanol at the pressure employed.

3. Method of treating low grade fatty stock containing at least 5% by weight of free fatty acids which comprises treating said stock with vapor of methanol at a temperature in the range of about 200 to 260 C. in the presence of an insoluble inorganic catalyst comprising an inorganic oxide, to form methyl esters, and separating methyl ester from other reaction products, the by-product water formed in the esterification reaction being removed as formed, and said temperature being below the boiling point of glycerol and at least twice the boiling temperature of methanol at the pressure employed.

4. Method of treating low grade fatty stock containing at least 5% by weight of free fatty acids which comprises treating said stock with vapor of methanol at a temperature in the range of about 200 to 260 C. in the presence of an insoluble inorganic catalyst comprising an inorganic oxide to esterify free fatty acids, and separating a methyl ester from other reaction products, the by-product water formed in the esterification reaction being removed as formed, and said temperature being below the boiling point of glycerol and at least twice the boiling temperature of methanol at the pressure employed.

5. Method of treating low grade fatty stock containing at least 5% by weight of free fatty acids which comprises treating said stock with vapor of methanol at a temperature in the range of about 200 to 260 C. in the presence of an insoluble inorganic catalyst comprising an inorganic oxide to esterify free fatty acids and alcoholyse at least part of the glyceride, and separating a methyl ester from other reaction products, the by-product water formed in the esterification reaction being removed as formed,

and said temperature being below the boiling point of glycerol and at least twice the boiling temperature of methanol at the pressure employed.

6. Method of treating low grade fatty stock containing at least 5% by weight of free fatty acids which comprises treating said stock with vapor of methanol at a temperature in the range of about 200 to 260 C. in the presence of an insoluble inorganic catalyst comprising alumina to form methyl esters, and separating a methyl ester from the reaction mass, the byproduct water formed in the esterification reaction being removed as formed, and said temperature being below the boiling point of glycerol and at least twice the boiling temperature of methanol at the pressure employed.

'7. Continuous method of treating low grade fatty stock containing at least 5% by weight of free fatty acids which comprises continuously treating said stock with a countercurrent flow of vapor of methanol at a temperature in the range of about 200 to 260 C., in the presence of a stationary bed of pelleted insoluble inorganic catalyst comprising alumina at a fatty stock throughput rate below that which floods the catalyst bed, to form ethyl esters, and sepa rating methyl esters from the reaction mass, the by-product water formed in the esterification reaction being removed as formed, and said temperature being below the boiling point of glycerol and at least twice the boiling temperature of methanol at the pressure employed.

8. Method of preparing lower alkyl esters which comprises treating fatty glyceride stock containing free fatty acids with vapor of a lower alkanol at a temperature above about 150 C. and below decomposition temperatures of the alkanol in the presence of an insoluble inorganic oxygenated material as catalyst to form alkyl esters, separating the liquid reaction mass from the catalyst, treating said liquid mass with liquid lower alkanol in the presence of an alkaline catalyst, and separating lower alkyl esters from the reaction mass, the by-product water formed in the esterification reaction being removed as formed, and said temperature being above the boiling temperature of the lower alkanol at the pressure employed.

9. Method of treating low grade fatty glyceride stock containing at least 5% by weight of free fatty acids which comprises treating said stock with vapor of a lower alkanol at a, temperature above about 200 and below the alkanol decomposition temperature in the presence of an insoluble catalyst comprising an inorganic oxide to form alkyl esters, separating the liquid reaction mass from the catalyst, treating said liquid mass with liquid lower alkanol in the presence of an alkaline catalyst, and separating lower alkyl esters from the reaction mass, the by-product water formed in the esterification reaction being removed as formed, and said temperature being above the boiling temperature of the lower alkanol at the pressure employed.

10. Method of treating low grade fatty glyceride stock containing at least 5% by weight of free fatty acids which comprises treating said stock with vapor of methanol at a temperature in the range of about 200 to 260 C. in the presence of an insoluble catalyst comprising alumina to form methyl esters, separating the liquid reaction mass from the catalyst, treating said liquid mass with liquid methanol in the 11 presence of an alkaline catalyst, and separating lower alkyl esters from the reaction mass, the by-product water formed in the esterification reaction being removed as formed, and said temperature being below the boiling point of glycerol and at'least twice the boiling temperature of methanol at the, pressure employed.

WILLIAM J. PATERSON.

12 REFERENCES ornzn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,881,563 Held Oct. 11, 1932 1,990,229 Friedolshein et a1. Feb. 5, 1935 2,383,579 Allen et a1. Aug. 28, 1945 

1. METHOD OF PREPARING LOWER ALKYL ESTERS OF FATTY ACIDS WHICH COMPRISES TREATING FATTY STOCK CONTAINING FREE FATTY ACIDS WITH VAPOR OF A LOWER ALKANOL AT A TEMPERATURE ABOVE ABOUT 150*C. AND BELOW DECOMPOSITION TEMPERATURES OF THE ALKANOL IN THE PRESENCE OF AN INSOLUBLE INORGANIC OXYGENATED MATERIAL AS CATALYST, THE BY-PRODUCT WATER FORMED IN THE ESTERIFICATION REACTION BEING REMOVED AS FORMED, AND SAID TEMPERATURE BEING ABOVE THE BOILING TEMPERATURE OF THE LOWER ALKANOL AT THE PRESSURE EMPLOYED. 